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C F Contant

Publications and source records attributed to C F Contant.

At least 55 records · Page 3Linked to original sources
PubMed1993

Spectral analysis of corticomotor evoked potentials in spinal cord injury. Part 2. Chronic studies.

Corticomotor evoked potentials (CMEPs) have been suggested to accurately reflect neurological function, particularly with regard to the integrity of the spinal cord. However, the utility of these potentials to evaluate graded, chronic injury has received little attention. Frequency analysis has been suggested by the authors to be a method of simplifying interpretation of these complex signals. Ischaemic spinal cord injuries were produced in rabbits causing mild, moderate, or severe neurological deficits. CMEPs were recorded before, during, immediately following, and three days after injury. Alterations in the features of the power spectra reflected the degree of neurological injury. CMEP power spectra may predict neurological outcome and augment currently used electrodiagnostic tests.

Animals↗
PubMed1993

The relationship between hormonal mediators and systemic hypermetabolism after severe head injury.

The relationships of hormonal mediators to the systemic hypermetabolism and catabolism of head injury were studied in 15 patients with severe head injuries. Resting energy expenditure (REE), urinary nitrogen balance, and plasma glucose concentration were measured daily for the first 2 weeks after injury as the major indicators of hypermetabolism. These dependent variables were correlated with daily measurements of urinary epinephrine, norepinephrine, metanephrine, normetanephrine, dopamine, and cortisol, and with plasma levels of insulin, glucagon, and C-reactive protein. Urinary catecholamine and cortisol excretion were markedly elevated in these patients throughout the 2 weeks of study. Catecholamine excretion peaked between days 7 and 10, whereas cortisol excretion tended to be highest on day 5 after injury. Urinary levels of norepinephrine, normetanephrine, and cortisol were highest in the two patients with Glasgow Coma Scale scores of 4. Plasma insulin and glucagon concentrations were elevated on day 1 after injury and tended to increase throughout the 2-week period of study. The variables significantly associated with REE were the severity of injury, reflected by the GCS score, the urinary excretion of norepinephrine during the first 2 days after injury, and the urinary excretion of epinephrine and norepinephrine during days 3 to 7 after injury. A negative nitrogen balance was associated with the urinary excretion of epinephrine and norepinephrine, with caloric balance, and with plasma C-reactive protein during days 1 and 2 after injury. During days 3 to 7, a negative nitrogen balance was associated with the urinary excretion of epinephrine and norepinephrine and with caloric balance, and during days 8 to 14, a negative nitrogen balance was associated primarily with urinary cortisol excretion.

Adult↗
PubMed1993

Hemophilia growth and development study. Design, methods, and entry data.

PURPOSE: The study design, research questions, and baseline data are presented from a multicenter longitudinal epidemiologic investigation of the impact of human immunodeficiency virus (HIV) infection on three areas of functioning in children and adolescents with hemophilia: physical growth and sexual maturation, immune function, and neurological and neuropsychological functioning. PATIENTS AND METHODS: Sixty-nine percent (n = 333) of a population of males between the ages of 6 and 19 years with moderate to severe hemophilia participated in a comprehensive baseline examination. Approximately 62% of the study group was HIV seropositive and 38% HIV seronegative. RESULTS: Adjusted for age, HIV-positive participants were three times as likely as HIV-negative participants to exhibit declines in height-for-age attainment (p = 0.05), twice as likely to have delays in sexual maturation (p = 0.414), and more than three times as likely to exhibit antibody levels that were not indicative of prior exposure or vaccination (p < 0.001). In addition, analysis of a comprehensive battery of neuropsychological tests showed that HIV-positive participants were 50% more likely to show scores approximately 1 SD below expected levels in three of nine functional areas (p = NS) compared with HIV-negative participants. CONCLUSIONS: Entry data for this study reveal a greater likelihood for HIV-positive children and adolescents with moderate to severe hemophilia to have abnormal growth, and to exhibit antibody levels not indicative of prior exposure to disease or vaccination, which could be attributed to HIV infection. Lowered neuropsychological test performance in both groups may be attributable to the deleterious effects of chronic illness. Data are being collected from a group of non-HIV infected non-hemophiliac siblings for comparison.

Adolescent↗
PubMed1993

Phenobarbital and cerebral blood flow during hypotension in newborn pigs.

Phenobarbital sodium (PhS) has been used in anticonvulsant concentrations in premature newborns in attempts to prevent peri- and intraventricular hemorrhages (PIVH). Its effectiveness in preventing PIVH in clinical situations is still uncertain; however, PhS has reduced PIVH after hypertension in newborn beagles, and it has lowered cerebral blood flow (CBF) during hypertension in newborn beagles and piglets. We hypothesized that PhS might reduce CBF during systemic hypotension. Twelve control and 12 PhS-treated piglets (1 to 2 d old) were used for microsphere determinations of CBF during 1) steady state; 2) 30 min after PhS (treatment group) or saline infusion (controls); and 3 and 4) during two levels of graded hypotension. Mean arterial blood pressure (MABP) was 61 +/- 13 (SD) mm Hg (controls) and 57 +/- 13 (SD) mm Hg (PhS) during steady state. Thirty min after the PhS or saline infusion, MABP and CBF remained unchanged in both groups. CBF during hypotension at MABP of 41 +/- 5 (SD) mm Hg was significantly higher in controls than was CBF at MABP of 39 +/- 6 (SD) mm Hg in the PhS-treated group (p = 0.044); CBF in the two groups during the second hypotensive phase was not significantly different. However, LOWESS regression suggested that the CBF from the controls dropped as the arterial pressure decreased to less than 37 mm Hg, whereas PhS treatment lowered CBF during hemorrhagic hypotension compared with controls at blood pressures greater than 37 mm Hg but did not lower CBF further at lower systemic blood pressures.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Effects of human immunodeficiency virus and immune status on magnetic resonance imaging of the brain in hemophilic subjects: results from the hemophilia growth and development study.

To determine the effects of hemophilia and human immunodeficiency virus (HIV) infection on the nervous system, the authors examined the relationship of brain magnetic resonance imaging (MRI) findings to immunologic function and neurologic examination findings. Baseline examinations included physical and neurologic examination, immunologic and virologic testing, and MRI of the brain. On neurologic examination, muscle atrophy was considered to be related to hemophilia if adjacent joints had arthropathy due to bleeding. Muscle atrophy was considered non-hemophilia-related if unrelated to arthropathy or if muscle atrophy was diffuse. Subjects were boys aged 6 to 19 years, enrolled in a multicenter study of the effects of hemophilia and HIV infection on growth and development, all with congenital coagulopathies requiring factor infusions. Three hundred ten subjects had complete data including neurologic examination, T-cell subsets, HIV antibodies, and MRI. Subjects with HIV infection whose CD4+ counts were < 200/microL were compared with subjects with HIV infection and CD4+ counts > or = 200/microL and with HIV-negative subjects, all of whom had CD4+ counts > 200/microL. MRI studies were normal in 230. Abnormal MRI studies were more frequent in HIV-positive subjects with CD4+ counts < 200 (29.4% abnormal compared with 17% in HIV-positive subjects with CD4+ counts > or = 200 and 15.3% in HIV-negative subjects). Diffuse atrophy accounted for most of the excess abnormalities in HIV-positive subjects with CD4+ counts < 200 (77.3% of abnormal scans). Diffuse atrophy on MRI was associated with decreased muscle bulk on neurologic examination, but not with abnormal tendon reflexes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Neurologic history and examination results and their relationship to human immunodeficiency virus type 1 serostatus in hemophilic subjects: results from the hemophilia growth and development study.

In a prospective study of the growth and neuropsychologic function of hemophilic subjects, 333 boys, median age of 12.3 years, had baseline neurologic examinations. The study population included 207 individuals (62%) who were seropositive for human immunodeficiency virus type 1 (HIV-1). Overall results indicated that 11% had abnormalities of cranial nerve function, 17% had abnormal deep tendon reflexes, 23% had abnormal strength, 25% had abnormal coordination, and 31% had abnormal tone, bulk, or range of motion. By contrast, 2% or fewer displayed abnormal movements or had abnormal pain or vibratory sensation, or altered mental status. Abnormalities were more common in older hemophilic subjects (eg, 67 [38%] of 177 subjects > or = 12 years of age had abnormal tone, bulk, or range of motion vs 36 [23%] of 156 subjects < 12 years of age). When compared with regard to HIV-1 status, HIV-seronegative and HIV-seropositive subjects did not differ with regard to head circumference or the frequency of abnormalities of cranial nerve function, sensation, muscle strength, or coordination. However, deep tendon reflexes and tone, bulk, or range of motion were more frequently abnormal in HIV-1-seropositive individuals. More HIV-1-positive subjects had at least one increased deep tendon reflex (13/207 [6.3%] vs 1/126 [0.8%] in seronegatives) and more had non-hemophilia-related decreases in muscle bulk (7/207 [3.4%] vs 0/126 in seronegatives). These results indicate that hemophilia causes substantial neurologic dysfunction and that certain findings, such as changes in muscle-stretch reflexes or muscle bulk, may also reflect the neurologic consequences of HIV infection.

Adolescent↗
PubMed1992

Cerebral blood flow, arteriovenous oxygen difference, and outcome in head injured patients.

Cerebral blood flow (CBF) and other physiological variables were measured repeatedly for up to 10 days after severe head injury in 102 patients, and CBF levels were related to outcome. Twenty five of the patients had a reduced CBF [mean (SD) 0.29 (0.05) ml/g/min]; 47 had a normal CBF, (0.41 (0.10) ml/g/min); and 30 had a raised CBF (0.62 (0.14) ml/g/min). Cerebral arteriovenous oxygen differences were inversely related to CBF and averaged 2.1 (0.7) mumol/ml in the group with reduced CBF, 1.9 (0.5) mumol/ml in the group with normal CBF, and 1.6 (0.4) mumol/ml in the group with raised CBF. Patients with a reduced CBF had a poorer outcome than patients with a normal or raised CBF. Mortality was highest in patients with a reduced CBF, and was 32% at three months after injury, whereas only 21% of the patients with a normal CBF and 20% of the patients with a raised CBF died. There were no differences in the type of injury, initial score on the Glasgow Coma Scale, mean intracranial pressure (ICP), highest ICP, or the amount of medical treatment required to keep the ICP less than 20 mm Hg in each group. Systemic factors did not significantly contribute to the differences in CBF among the three groups. A logistic regression model of the effect of CBF on neurological outcome was developed. When adjusted for variables which were found to be significant confounders, including age, initial Glasgow Coma Score, haemoglobin concentration, cerebral perfusion pressure and cerebral metabolic rate of oxygen, a reduced CBF remained significantly associated with an unfavourable neurological outcome.

Adult↗
PubMed1992

Brain abnormalities in male children and adolescents with hemophilia: detection with MR imaging. The Hemophilia Growth and Development Study Group.

Cranial magnetic resonance (MR) imaging was performed in 124 male patients (aged 7-19 years), from 14 institutions, in whom a diagnosis of moderate to severe hemophilia was made. Blood tests in all subjects were negative for human immunodeficiency virus. Findings in MR studies were abnormal in 25 (20.2%) subjects. Six lesions in five subjects were classified as congenital. The most commonly identified congenital lesion was a posterior fossa collection of cerebrospinal fluid (five cases). Twenty-two subjects had acquired lesions that were probably related to the hemophilia or its treatment. The most commonly acquired lesions were single- or multifocal areas of high signal intensity within the white matter on T2-weighted images noted in 14 (11.3%) subjects. Two subjects had large focal areas of brain atrophy, and six had some degree of diffuse cerebral cortical atrophy. Three subjects (2.4%) had hemorrhagic lesions. To the authors' knowledge, the unexpected finding of small, focal, nonhemorrhagic white matter lesions has not previously been reported.

Adolescent↗
PubMed1992

Effect of head elevation on intracranial pressure, cerebral perfusion pressure, and cerebral blood flow in head-injured patients.

The traditional practice of elevating the head in order to lower intracranial pressure (ICP) in head-injured patients has been challenged in recent years. Some investigators argue that patients with intracranial hypertension should be placed in a horizontal position, the rationale being that this will increase the cerebral perfusion pressure (CPP) and thereby improve cerebral blood flow (CBF). However, ICP is generally significantly higher when the patient is in the horizontal position. This study was undertaken to clarify the issue of optimal head position in the care of head-injured patients. The effect of 0 degree and 30 degrees head elevation on ICP, CPP, CBF, mean carotid pressure, and other cerebral and systemic physiological parameters was studied in 22 head-injured patients. The mean carotid pressure was significantly lower when the patient's head was elevated at 30 degrees than at 0 degrees (84.3 +/- 14.5 mm Hg vs. 89.5 +/- 14.6 mm Hg), as was the mean ICP (14.1 +/- 6.7 mm Hg vs. 19.7 +/- 8.3 mm Hg). There was no statistically significant change in CPP, CBF, cerebral metabolic rate of oxygen, arteriovenous difference of lactate, or cerebrovascular resistance associated with the change in head position. The data indicate that head elevation to 30 degrees significantly reduced ICP in the majority of the 22 patients without reducing CPP or CBF.

Adult↗
PubMed1992

Continuous monitoring of jugular venous oxygen saturation in head-injured patients.

The continuous measurement of jugular venous oxygen saturation (SjvO2) with a fiberoptic catheter is evaluated as a method of detecting cerebral ischemia after head injury. Forty-five patients admitted to the hospital in coma after severe head injury had continuous and simultaneous monitoring of SjvO2, intracranial pressure, arterial oxygen saturation, and end-tidal CO2. Cerebral blood flow, cerebral metabolic rates of oxygen and lactate, arterial and jugular venous blood gas levels, and hemoglobin concentration were measured every 8 hours for 1 to 11 days. Whenever SjvO2 dropped to less than 50%, a standardized protocol was followed to confirm the validity of the desaturation and to establish its cause. Correlation of SjvO2 values obtained by catheter and with direct measurement of O2 saturation by a co-oximeter on venous blood withdrawn through the catheter was excellent after in vivo calibration when there was adequate light intensity at the catheter tip (176 measurements: r = 0.87, p less than 0.01). A total of 60 episodes of jugular venous oxygen desaturation occurred in 45 patients. In 20 patients the desaturation value was confirmed by the co-oximeter. There were 33 episodes of desaturation in these 20 patients, due to the following causes: intracranial hypertension in 12 episodes, hypocarbia in 10, arterial hypoxia in six, combinations of the above in three, systemic hypotension in one, and cerebral vasospasm in one. The incidence of jugular venous oxygen desaturations found in this study suggests that continuous monitoring of SjvO2 may be of clinical value in patients with head injury.

Adult↗
PubMed1992

Cerebral blood flow, AVDO2, and neurologic outcome in head-injured patients.

A reduced cerebral blood flow (CBF) and a widened arteriovenous oxygen difference (AVDO2) almost always have been associated with a poor neurologic outcome. The literature on this relationship is reviewed. A logistic regression analysis model of the effect of CBF on neurologic outcome was developed, which was adjusted for various confounding factors. CBF remained significantly associated with neurologic outcome-despite these adjustments.

Adult↗
PubMed1991

Evaluation of the Leeds prognostic score for severe head injury.

According to the Leeds scale for identifying severely head injured patients, death can be predicted with certainty within 12 hours of admission if a patient has a score higher than 13. The withdrawal of treatment from such patients has considerable moral and legal implications. Therefore, to test the reliability of the Leeds scale, it was applied to two patient populations with severe head injuries (479 retrospectively, 131 prospectively). In both groups the scale failed to predict mortality with 100% accuracy: in the first group, 16 of 23 (69.6%) of the patients with a score of more than 13 (and therefore predicted to die) died, and 380 (83.3%) of 456 patients with scores of 13 or less survived; the data for the second group are 6/10 (60%) and 98/121 (81%), respectively. The findings suggest that the Leeds prediction model is not infallible and should be applied cautiously when making decisions about the early termination of care in severely head injured patients.

Adolescent↗
PubMed1991

Epidemiological characteristics of subarachnoid hemorrhage in an urban population.

Several risk factors for unfavorable outcome from subarachnoid hemorrhage (SAH) have been identified. The prevalence of such risk factors varies among ethnic groups and among men and women. The influence of ethnic background and gender as factors in the outcome after SAH has not been adequately studied and is the focus of the present investigation. Outcome in 145 consecutive patients was dichotomized as good and moderately disabled vs severely disabled, vegetative, and dead. A multiple logistic regression model was used to examine the factors of gender, ethnic group (white and non-white), age, admission neurological grade, pre-existing hypertension, and intravenous drug abuse. Our data reveal that hypertensive, white males, with a history of intravenous drug abuse, have a high risk of unfavorable outcome following SAH. These observations are important for the design and interpretation of future studies relating to SAH.

Adolescent↗
PubMed1991

The effect of glucose administration on carbohydrate metabolism after head injury.

The role of intravenous infusion of glucose in limiting ketogenesis and the effect of glucose on cerebral metabolism following severe head injury were studied in 21 comatose patients. The patients were randomly assigned to alimentation with or without glucose. Systemic protein wasting, arterial concentrations of energy substrates, and cerebral metabolism of these energy substrates were monitored for 5 days postinjury. Both groups were in negative nitrogen balance, and had wasting of systemic proteins despite substantial protein intake. Blood and cerebrospinal fluid (CSF) glucose concentrations were highest on Day 1, but remained higher than normal fasting levels on all days of study, even in the patients who received no exogenous glucose. Although there were no differences in blood or CSF glucose concentrations in the two groups of patients, the glucose group had higher plasma insulin levels, with a mean +/- standard deviation of 14.8 +/- 7.3 microU/ml compared to 10.3 +/- 4.2 microU/ml in the saline group. The blood concentrations of beta-hydroxybutyrate, acetoacetate, pyruvate, glycerol, and the free fatty acids were higher in the saline group than in the glucose group. Cerebral oxygen consumption was similar in the two groups, while the cerebral metabolism of glucose and of the ketone bodies was dependent on whether glucose was administered. In the glucose group, glucose was the only energy substrate utilized by the brain. In the saline group, the ketone bodies beta-hydroxybutyrate and acetoacetate replaced glucose to the extent of 16% of the brain's total energy production. Cerebral lactate production and CSF lactate concentration were lower in the saline group. These studies suggest that administration of glucose during the early recovery period of severe head injury is a major cause of suppressed ketogenesis, and may increase production of lactic acid by the traumatized brain by limiting the availability of nonglycolytic energy substrates.

3-Hydroxybutyric Acid↗
PubMed1991

The influence of diabetes mellitus on outcome from subarachnoid hemorrhage.

Diabetes mellitus (DM) has been shown to be a risk factor for subarachnoid hemorrhage (SAH). However, the influence of this disease on outcome from SAH has not been adequately studied. We retrospectively reviewed 150 patients with SAH, including 22 with and 128 without DM. Our results indicate that pre-existing DM does not significantly influence outcome from SAH when examined in conjunction with other chronic diseases and epidemiological factors.

Adult↗
PubMed1989

Clinical experience with a continuous monitor of intracranial compliance.

Intracranial compliance, as estimated from a computerized frequency analysis of the intracranial pressure (ICP) waveform, was continuously monitored during the acute postinjury phase in 55 head-injured patients. In previous studies, the high-frequency centroid (HFC), which was defined as the power-weighted average frequency within the 4- to 15-Hz band of the ICP power density spectrum, was found to inversely correlate with the pressure-volume index (PVI). An HFC of 6.5 to 7.0 Hz was normal, while an increase in the HFC to 9.0 Hz coincided with a reduction in the PVI to 13 ml and indicated exhaustion of intracranial volume-buffering capacity. The mean HFC for individual patients in the present study ranged from 6.8 to 9.0 Hz, and the length of time that the HFC was greater than 9.0 Hz ranged from 0 to 104.8 hours. The mortality rate increased concomitantly with the mean HFC, from 7% when the mean HFC was less than 7.5 Hz to 46% when the mean HFC was 8.5 Hz or greater. The length of time that the HFC was 9.0 Hz or greater was also associated with an increased mortality rate, which ranged from 16% if the HFC was never above 9.0 Hz to 60% if the HFC was 9.0 Hz or greater for more than 12 hours. In 12 patients who developed uncontrollable intracranial hypertension or clinical signs of tentorial herniation during the monitoring period, 75% were observed to have had an increase in the HFC to 9.0 Hz or more 1 to 36 hours prior to the clinical decompensation. The more rapid the increase in the HFC, the more likely the deterioration was to be caused by an intracranial hematoma. Continuous monitoring of intracranial compliance by computerized analysis of the ICP waveform may provide an earlier warning of neurological decompensation than ICP per se and, unlike PVI, does not require volumetric manipulation of intracranial volume.

Adaptation, Physiological↗
PubMed1988

High-dose barbiturate control of elevated intracranial pressure in patients with severe head injury.

In a five-center study, 73 patients with severe head injury and elevated intracranial pressure (ICP) were randomly assigned to receive either a regimen that included high-dose pentobarbital or one that was otherwise similar but did not include pentobarbital. The results indicated a 2:1 benefit for those treated with the drug with regard to ICP control. When patients were stratified by prerandomization cardiac complications, the advantage increased to 4:1. A multiple logistic model considering treatment and selected baseline variables indicated a significant positive treatment effect of barbiturates, a significant effect of time from injury to randomization, and an interaction of treatment with cardiovascular complications. However, of 925 patients potentially eligible for randomization, only 12% met ICP randomization criteria. The results support the hypothesis that high-dose pentobarbital is an effective adjunctive therapy, but that it is indicated in only a small subset of patients with severe head injury.

Adolescent↗